剑指Offer 56. 删除链表中重复的结点 （链表）

题目描述

在一个排序的链表中，存在重复的结点，请删除该链表中重复的结点，重复的结点不保留，返回链表头指针。 例如，链表1->2->3->3->4->4->5 处理后为 1->2->5

题目地址

https://www.nowcoder.com/practice/fc533c45b73a41b0b44ccba763f866ef?tpId=13&tqId=11209&tPage=3&rp=3&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking

思路

要删除有序链表中所有的重复节点，而头结点有可能就是重复节点。这样的比较好的解决方式就是新建头结点，然后往后遍历，同样的值就全部略过。

Python

# -*- coding:utf-8 -*-
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None

node1 = ListNode(1)
node2 = ListNode(2)
node3 = ListNode(3)
node4 = ListNode(3)
node5 = ListNode(4)
node6 = ListNode(4)
node7 = ListNode(5)
node1.next = node2
node2.next = node3
node3.next = node4
node4.next = node5
node5.next = node6
node6.next = node7

class Solution:
    def deleteDuplication(self, pHead):
        # write code here
        if not pHead or not pHead.next:
            return pHead
        first = ListNode(-1)
        first.next = pHead
        last = first
        cur = pHead
        while cur and cur.next:
            if cur.val != cur.next.val:
                cur = cur.next
                last = last.next
            else:
                val = cur.val
                while cur and cur.val == val:
                    cur = cur.next
                last.next = cur
        return first.next

if __name__ == '__main__':
    result = Solution().deleteDuplication(node1)
    while result:
        print(result.val, end = ' ')
        result = result.next